1. Field of the Invention
The present invention relates generally to laser printers and particularly to their arrangements attaching a toner cartridge.
2. Description of the Background Art
A laser printer arranges toner on a surface of a photoreceptor drum charged by laser light and sandwiches a sheet between the photoreceptor drum and a transfer roller to place the toner on a surface of the sheet or the like in a shape to be transferred. The toner placed on the surface of the sheet or the like is fixed on the sheet or the like by a fixture roller and thus discharged.
Generally toner is accommodated in an exchangeable toner cartridge. When the toner runs out, the toner cartridge is exchanged to resupply toner. The toner cartridge is formed to be detachably attached to the laser printer.
FIG. 7 is a diagram for illustrating a toner cartridge arranged internal to a laser printer. FIG. 7 is a perspective view of the laser printer as seen in a plane. A toner cartridge 1 is arranged internal to a casing 45. In this example, toner cartridge 1 is formed substantially in a rectangle as seen in a plane. Toner cartridge 1 accommodates an agitator plate 39 agitating the internal toner and a developer roll 38 operated to transfer the toner on a photoreceptor drum.
Agitator plate 39 is formed in a plate, and formed substantially in a rectangle as seen in a plane. Agitator plate 39 can pivot around an axis at the plate's end corresponding to one side of the rectangle as seen in a plane. As agitator plate 39 pivots, the toner in toner cartridge 1 is agitated. Furthermore, developer roll 38 is formed in a column and rotates around the column's center axis.
As described above, toner cartridge 1 is internally provided with agitator plate 39 and other movable member. These members are actuated by force transmitted outside toner cartridge 1 via a coupling 56. More specifically, the laser printer's main body transmits the force via coupling 56 for actuation.
In FIG. 7, toner cartridge 1 is adapted to be detachably attachable to the printer's main body in a direction 68. Coupling 56 is adapted to be movable as indicated by an arrow 60. Coupling 56 is formed to have a portion inserted into and detached from toner cartridge 1.
When toner cartridge 1 is attached to the laser printer, toner cartridge 1 receives the coupling 56 insert to engage coupling 56 and a linking portion internal to toner cartridge 1. The coupling rotates around an axis parallel to the direction of the insertion to transmit force into toner cartridge 1 for actuation. When toner cartridge 1 is removed, coupling 56 is detached from toner cartridge 1.
FIG. 8 is a diagram for illustrating coupling 56 based on conventional art and a portion of toner cartridge 1 with which coupling 56 is engaged. Coupling 56 is supported by a support frame 21 formed internal to the casing.
Coupling 56 includes a gear 50, a presser 55, and an insert 53 inserted into a coupling insertion hole 11 formed in toner cartridge 1. By inserting insert 53 into coupling insertion hole 11 the rotational movement of gear 50 can be transmitted to toner cartridge 1.
To attach toner cartridge 1, toner cartridge 1 is inserted in a direction parallel to an end surface of insert 53, as indicated by an arrow 71. Gear 50 is formed to be movable in a direction parallel to that toward the toner cartridge 1. To exchange toner cartridge 1 the coupling 56 insert 53 recedes from coupling insertion hole 11 of toner cartridge 1. Furthermore when coupling 56 has toner cartridge 1 attached thereto, insert 53 is inserted in coupling insertion hole 11.
FIGS. 9 and 10 are diagrams for illustrating an arrangement for moving the coupling's insert. FIGS. 9 and 10 are side views of coupling 56. As shown in FIG. 9, coupling 56 includes gear 50, and first and second coupling members 51 and 52. Insert 53 is formed at the first coupling member 51. Insert 53 is formed to penetrate the second coupling member 52. Insert 53 is formed in a column.
The first coupling member 51 has a side surface provided with presser 55 in the form of a plate. The second coupling member 52 has a portion having a side surface inclined. The second coupling member 52 is set in the first coupling member 51 at an inclined portion 58, as indicated by an arrow 69.
The second coupling member 52 is fixed to the support frame immovably. The first coupling member 51 is rotatable around the columnar center axis of insert 53. When toner cartridge 1 is attached to the printer, insert 53 protrudes from a surface of the second coupling member 52, as shown in FIG. 9.
Presser 55 is connected for example to a door arranged at a front surface of the cartridge of the laser printer and for example by opening the door presser 55 is pushed (or pulled).
FIG. 10 is a side view with the first coupling member 51 rotated. As the first coupling member 51 rotates, the first coupling member 51 moves along the geometry of inclined portion 58 in a direction 70. Accordingly, insert 53 protruding from the surface of the second coupling member 52 moves in direction 70 and recedes from the toner cartridge's coupling insertion hole. Thus the insert protrudes from/recedes into the surface of the second coupling member 52.
Other than the above, Japanese Patent Laying-Open No. 2003-345130 discloses an image formation apparatus including a development frame pressing a development roller to contact a photoreceptor drive, and a lock member restricted in movement as an actuation rod moves. The publication discloses that in this image formation apparatus an unlocking member can perform one return operation to disengage and unlock the photoreceptor drum and the development roller to extract a toner cartridge.
In the FIGS. 8–10 conventional art laser printer the door located at a front side of the toner cartridge is opened and closed to push (or pull) the coupling's presser and thus insert the coupling's insert into the toner cartridge's coupling insertion hole and allow the insert to recede from the hole.
The above described coupling's structure is, however, significantly complicated and thus contributes to poor productivity. Furthermore, it requires a large number of components resulting in poor productivity. The image formation apparatus disclosed in the above publication is also disadvantageous in that it has a complicated structure and furthermore requires a large number of components, which renders expensive a laser printer to be manufactured.